The Na ion, K ion pump, manifested in broken cell preparations as a Na ion, K ion-ATPase activity, is important in the normal function of kidney, brain, heart and many other tissues. The enzymic mechanism of this pump involves a Na ion-dependent phosphorylation by ATP and a subsequent K ion-dependent dephosphorylation, but how this process produces transport of Na ion and K ion is not yet understood. Purified preparations of Na ion, K ion-ATPase contain at least two polypeptide subunits, but how these subunits are arranged to produce energy-linked vectorial ion movement is not known. Resolving the role of each subunit is hampered by the fact that dissociation of pump structure results in loss of Na ion, K ion-ATPase activity. The research proposed here is unique in that its objective is the isolation and purification of pump components without concern over this loss of ATPase activity. The key elements in this approach are two "partial" reactions catalyzed by the Na ion, K ion-ATPase: a Na ion-dependet ADP-ATP exchange and a K ion-dependent acetyl phosphatase activity. Our studies have shown that digitonin will disrupt membrane structure so that Na ion, K ion-ATPase activity is lost, but Na ion-dependent ADP-ATP exchange and K ion-dependent phosphatase activities survive. The surviving "partial" activities are solubilized by this treatment and represent the starting material for purification of active fragments of the Na ion, K ion pump. Enzymic characterization of the surviving activities is also underway.